Swine flu preoccupies world health leaders

May 14 2009

It is expected that the upcoming World Health Organisation's (WHO) annual assembly will be dominated this year by the emergence and spread of the new influenza virus H1N1 (swine flu).

The meeting in Geneva was due to continue from May 18th through to the 27th but is now expected to be curtailed to five days so the health ministers, from 193 countries, can return home to deal with the new virus.

Other issues are likely to be overshadowed by the emergence and spread of the new flu virus which prompted WHO Director-General Margaret Chan to announce that a global pandemic is imminent and discussions on several topics including international chemicals management, drug-resistant tuberculosis, food safety, viral hepatitis, counterfeit medical products, human organ and tissue transplantation, Chagas disease and the WHO's role and responsibilities in health research, are expected to be postponed until 2010.

Worldwide public health officials are closely monitoring the movements of the virus and watching for indications of it mutating and the assembly will focus on the world's readiness for a H1N1 pandemic and the efforts needed to ensure developing countries can access the antiviral drugs necessary to fight the new virus.

Scientists say the new hybrid flu is a mixture of swine, bird and human viruses and the development of an effective vaccine will be a major topic.

Dr. Chan is reportedly meeting pharmaceutical companies to discuss a change in production to H1N1 vaccines from, or alongside, those for seasonal flu but many experts favour the continued development of seasonal flu vaccines because the more common virus kills up to 500,000 people a year - new pandemic vaccine could be added to the seasonal flu shot or made separately.

The elderly and people with other health problems such as asthma appear most susceptible to pneumonia and other severe symptoms from both flu viruses - at least 20 companies worldwide make flu vaccines, including Sanofi-Aventis, Novartis, Baxter International, Australia's CSL, and nasal spray maker MedImmune, now part of AstraZeneca.

Mexico's ambassador to the United Nations in Geneva says his country, considered the epicentre of the H1N1 strain, will raise concerns about "discriminatory" measures imposed in response to the flu outbreak, such as forced quarantines and trade bans.

Mexico has had 60 confirmed deaths from the infection, the United States 3 deaths and Canada and Costa Rica one each but elsewhere, the virus appears to be causing milder symptoms, similar to those with the seasonal flu.

The WHO has confirmed 6,497 cases of influenza A(H1N1) infection in 33 countries worldwide but is not recommending travel or trade restrictions due to the outbreak and has said most patients can recover without drugs, though severe cases can be treated with antivirals such as Tamiflu (Roche) or Relenza (GlaxoSmithKline).

The WHO says as of the 14th May 2009, apart from the countries already mentioned, the following countries have reported laboratory confirmed cases with no deaths - Argentina (1), Australia (1), Austria (1), Brazil (8), China (4), Colombia (7), Cuba (1), Denmark (1), El Salvador (4), Finland (2), France (14), Germany (12), Guatemala (3), Ireland (1), Israel (7), Italy (9), Japan (4), Netherlands (3), New Zealand (7), Norway (2), Panama (29), Poland (1), Portugal (1), Republic of Korea (3), Spain (100), Sweden (2), Switzerland (1), Thailand (2), and the United Kingdom (71).

The WHO says individuals who are ill should delay travel plans and returning travellers who fall ill should seek appropriate medical care.

The WHO says the major determinant of the severity of an influenza pandemic, as measured by the number of cases of severe illness and deaths it causes, is the inherent virulence of the virus, but many other factors influence the overall severity of a pandemic’s impact and even a pandemic virus that initially causes mild symptoms in otherwise healthy people can be disruptive.

Also the same virus that causes mild illness in one country can result in much higher morbidity and mortality in another and the inherent virulence of the virus can change over time as the pandemic goes through subsequent waves of national and international spread.

An influenza pandemic is caused by a virus that is either entirely new or has not circulated recently and widely in the human population and this creates an almost universal vulnerability to infection and though not everyone become infected during a pandemic, almost everyone is susceptible and pandemics are socially and economically disruptive, with a potential to temporarily overburden health services.

The WHO says the contagiousness of the virus will influence the speed of spread, both within countries and internationally and this, too, can influence severity, as very rapid spread can undermine the capacity of governments and health services to cope.

People with underlying chronic conditions, such as cardiovascular disease, hypertension, asthma, diabetes, rheumatoid arthritis, and several others, are more vulnerable as they are more likely to experience severe or lethal infections.

Pandemics also tend to encircle the globe in at least two and sometimes three, waves and the severity of subsequent waves can differ dramatically in most countries.

Influenza viruses also mutate frequently and unpredictably and the emergence of an inherently more virulent virus during the course of a pandemic is always possible - the 1918 pandemic began mild and returned, within six months, in a much more lethal form.

The same virus that causes only mild symptoms in countries with strong health systems can be devastating in other countries where health systems are weak, supplies of medicines, including antibiotics, are limited or frequently interrupted, and hospitals are crowded, poorly equipped, and under-staffed.

The WHO says the H1N1 virus is a new virus that has not been seen previously in either humans or animals and scientists suspect that pre-existing immunity to the virus will be low or non-existent, or largely confined to older population groups.

H1N1 appears to be more contagious than seasonal influenza and apart from the outbreak in Mexico, which the WHO says is still not fully understood, the H1N1 virus tends to cause very mild illness in otherwise healthy people and nearly all cases of illness, and all deaths, have been detected in people with underlying chronic conditions and this is of particular concern.

Scientists are concerned about possible changes that could take place as the virus spreads to the southern hemisphere and encounters currently circulating human viruses as the normal influenza season in that hemisphere begins.

The fact that the H5N1 avian influenza virus (bird flu) is firmly established in poultry in some parts of the world is another worry because it is impossible to predict how the H5N1 virus will behave under the pressure of a pandemic.

At present, H5N1 is an animal virus that does not spread easily to humans and only very rarely transmits directly from one person to another.

H1N1 flu spreads in the same way that regular seasonal influenza viruses spread - mainly through the coughs and sneezes of people who are sick with the virus.